From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 8E8534F93DC; Thu, 1 Oct 2026 21:18:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790889493; cv=none; b=rHFdsvCtn30Pf8o+rMla8tdqmN/VHXq3G48jwr0wptQECg2KF51K67eTGpsFDJvKv0ba5ISogz6Zf8I4d7E7I0ESA7HiCD4QeHgDsu+2jvmMLVXm8Tp2YDSGUnP/HvnEGpDx9Cu9lDQYk8wYY5XlJv9j/24Zfdl7Cfm/62CIOw0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790889493; c=relaxed/simple; bh=QTDzI9TFR5poyDcHbXwN5yB0vq+wEkyrdEszsBvl/zE=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=ebr3hv5PKNQy08zrJboJxPCO8uLPu1xS6LjzWTmktHfJ8Fzr55Ut2PIBzowHyNz6zzHkhoXQSaSCxY1C/QU3aJZOvvavtSON+H5IyszueTNQ1I3/9k2E1nAFceOfP4w3IShO2ufH2ShSuuO/dSj6uf1rBHyCCFq8YlTpvp3xHNE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=KuEUnD1L; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="KuEUnD1L" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 797821476; Thu, 1 Oct 2026 14:18:06 -0700 (PDT) Received: from e129823.arm.com (e129823.arm.com [10.2.213.3]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E38223F86F; Thu, 1 Oct 2026 14:18:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1790889489; bh=QTDzI9TFR5poyDcHbXwN5yB0vq+wEkyrdEszsBvl/zE=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=KuEUnD1LIbrX/jzzm1mZU/5F3Ih+d9xB1/92+Mz5bXrOPOgmJGXD68Xo+HU4T+sjf uUJU6JOq70hPW4Su+HLIYp5N+9TfL8d/JnhxGV8zCiyqzp4bxpqN5IGQS4LtYIuAmn 7L/Vp08sWJtgtf1TkHBorBCIGw/zajASP6GMTtmY= From: Yeoreum Yun Date: Thu, 01 Oct 2026 22:17:51 +0100 Subject: [PATCH v9 1/4] kselftest: mm: prevent random failure of huge page split for khugepaged Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261001-fix_split-v9-1-0f4ba8bbdbdf@arm.com> References: <20261001-fix_split-v9-0-0f4ba8bbdbdf@arm.com> In-Reply-To: <20261001-fix_split-v9-0-0f4ba8bbdbdf@arm.com> To: Andrew Morton , David Hildenbrand , Lorenzo Stoakes , Zi Yan , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Shuah Khan , Kevin Brodsky Cc: linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Sarthak Sharma , Yeoreum Yun X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2774; i=yeoreum.yun@arm.com; h=from:subject:message-id; bh=QTDzI9TFR5poyDcHbXwN5yB0vq+wEkyrdEszsBvl/zE=; b=owEB7QES/pANAwAKAW3Vw9FaxTEzAcsmYgBqvs4JqSJ1v+3SCIVc/Qop0U3V/fHOG0In9DYc6 qk+W9AnCi2JAbMEAAEKAB0WIQQtg+CS3QUzuFh1pJ1t1cPRWsUxMwUCar7OCQAKCRBt1cPRWsUx M3GrDADMQ9d4L9YVcXONl31+8k2UAQroC+yDBfRk+kHoqTncqw/AFZd7JktlL4pZNsOiLhl9MB2 hjUqOHiPzndcOKMiKCugRHmoiZ21xvIi6JpbXGzNWuOV4KTKl5Zgti4LXttMFTpdKDYMK5FUhZe fNyFE5cpSyny5d8rKJk/C2KbwvnYGZvijDOzpHkidAbG75XD8fKx+TQPyA79E3on2eAYmbPw7cE QR9lMSNFU7tuau5RgRmRi6N256cX1Fm8S5D4gIvcD8tikyGWY76r0/EEstl12wedqXytcHQpCBD ThZt2haAqv9Gt0IiEfCNJgHrzDtxfjrjw3KCHs2aQF93T9M3Lq3QKdvq1+1GJ5nKrzuTf8hof7l VFd3Fop4Eef5hmAd5aa6Af9XUJpvc2p1aVH8aP3ZjdvefZsyUjt4GUeXLSPo74mCTn92X2cemAX a6NWDcoLLOaJS8FPkHShJtN0GUSFQKiKAY+gwmyp2QuuGBVDTh/Urk7XRGZY9jZUo+eRE= X-Developer-Key: i=yeoreum.yun@arm.com; a=openpgp; fpr=2D83E092DD0533B85875A49D6DD5C3D15AC53133 There're some random failure for split_huge_page_test when khugepaged collapses pages into pmd again which had split by the test. Prevent the khugepaged's collapses for split page by setting the mapped pmd-huge-page with MADV_NOHUGEPAGE before split. Suggested-by: Kevin Brodsky Suggested-by: Lorenzo Stoakes (ARM) Reviewed-by: Lorenzo Stoakes (ARM) Reviewed-by: Zi Yan Reviewed-by: Sarthak Sharma Acked-by: David Hildenbrand (Arm) Signed-off-by: Yeoreum Yun --- tools/testing/selftests/mm/split_huge_page_test.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c index c5d96a4b1db3..36a6719ff09a 100644 --- a/tools/testing/selftests/mm/split_huge_page_test.c +++ b/tools/testing/selftests/mm/split_huge_page_test.c @@ -108,6 +108,15 @@ static char *allocate_zero_filled_hugepage(size_t len) return result; } +static void disable_khugepaged(void *addr, size_t len) +{ + /* Disables khugepaged from collapsing pages in range into THPs */ + if (!madvise(addr, len, MADV_NOHUGEPAGE)) + return; + + ksft_exit_fail_perror("MADV_NOHUGEPAGE failed"); +} + static void verify_rss_anon_split_huge_page_all_zeroes(char *one_page, int nr_hpages, size_t len) { unsigned long rss_anon_before, rss_anon_after; @@ -120,6 +129,8 @@ static void verify_rss_anon_split_huge_page_all_zeroes(char *one_page, int nr_hp if (!rss_anon_before) ksft_exit_fail_msg("No RssAnon is allocated before split\n"); + disable_khugepaged(one_page, len); + /* split all THPs */ write_debugfs(PID_FMT, getpid(), (uint64_t)one_page, (uint64_t)one_page + len, 0); @@ -167,6 +178,8 @@ static void split_pmd_thp_to_order(int order) if (!check_huge_anon(one_page, 4 * pmd_pagesize, 4, pmd_pagesize)) ksft_exit_fail_msg("No THP is allocated\n"); + disable_khugepaged(one_page, len); + /* split all THPs */ write_debugfs(PID_FMT, getpid(), (uint64_t)one_page, (uint64_t)one_page + len, order); @@ -215,6 +228,8 @@ static void split_pte_mapped_thp(void) goto out; } + disable_khugepaged(thp_area, thp_area_size); + /* * To challenge spitting code, we will mremap a single page of each * THP (page[i] of thp[i]) in the thp_area into page_area. This will @@ -482,6 +497,7 @@ static int create_pagecache_thp_and_fd(const char *testfile, size_t fd_size, ksft_test_result_skip("Pagecache folio split skipped\n"); return -2; } + disable_khugepaged(*addr, fd_size); return 0; err_out_close: close(*fd); -- 2.43.0